Theoretical studies of collisionless shocks for laser-acceleration of ions

A. Stockem; F. Fiuza; E. Boella; R. A. Fonseca; L. O. Silva; C. Joshi; W. B. Mori

doi:10.1117/12.2018491

7 May 2013 Theoretical studies of collisionless shocks for laser-acceleration of ions

A. Stockem, F. Fiuza, E. Boella, R. A. Fonseca, L. O. Silva, C. Joshi, W. B. Mori

Proceedings Volume 8779, Laser Acceleration of Electrons, Protons, and Ions II; and Medical Applications of Laser-Generated Beams of Particles II; and Harnessing Relativistic Plasma Waves III; 87790B (2013) https://doi.org/10.1117/12.2018491
Event: SPIE Optics + Optoelectronics, 2013, Prague, Czech Republic

Abstract

Recently, strong effort has been done in exploring shock acceleration for the generation of highly energetic ion beams, with applications e.g. for medical purposes. The heating of a near-critical density plasma target with a laser, increases the electron temperature and excites ion acoustic waves, which can lead to electrostatic shock formation due to non-linear wave breaking. The higher inertia background ions are reflected and accelerated at the shock potential, showing a quasi-monoenergetic profile. For the first time, its feasibility has been demonstrated experimentally, gaining 20 MeV protons with a very narrow energy spread¹ and a predicted scaling up to 200 MeV for lasers with a₀ = 10.² In the quest for high proton energies, optimal conditions for shock formation have to be found. We developed a relativistic model that connects the initial parameters with the steady state shock Mach number, which is based on the Sagdeev approach,^{3, 4} showing an increase of the ion energy for high upstream electron temperatures and low downstream to upstream density ratios⁵ and high temperature ratios, which has been confirmed by particle-in-cell simulations. In the context of producing a quasi-monoenergetic beam profile, we studied the enhancement of the Weibel instability in an electrostatic shock setup. Governing parameter regimes for the transition to an electromagnetic shock, which is associated with a broadening of the ion spectrum, were determined analytically and confirmed with simulations.

Citation Download Citation

A. Stockem, F. Fiuza, E. Boella, R. A. Fonseca, L. O. Silva, C. Joshi, and W. B. Mori "Theoretical studies of collisionless shocks for laser-acceleration of ions", Proc. SPIE 8779, Laser Acceleration of Electrons, Protons, and Ions II; and Medical Applications of Laser-Generated Beams of Particles II; and Harnessing Relativistic Plasma Waves III, 87790B (7 May 2013); https://doi.org/10.1117/12.2018491

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available